With Emma Back
For some time, malaria experts working along the Thailand-Cambodia border have been worried. They saw signs that malaria patients were responding less well to treatment, even with the newest and most effective drugs - namely artemisinin-based combination therapies (ACTs).
Now, sadly, it's more than an ugly rumor. The New York Times reported last week on recent studies confirming that malarial parasites circulating in this region have indeed become less responsive to artemisinin (which is often used alone here, rather than in combination, thereby driving resistance). Where it used to take only two days to kill enough malarial parasites with ACTs to cure a case of malaria, it can now take five days, allowing the parasite to go through several reproductive cycles in the body. That's a heart-breaking difference when you're the parent or carer of a feverish child. It's also a wide open door for mosquitoes to ingest blood filled with resistant parasites and spread it to their next victim.
Time is crucial in the fight against drug resistance, and those concerned about anti-malarial resistance have been losing the battle for time. While many older drugs work some of the time in some regions, ACTs stand alone in effectiveness and reliability. Or at least they did until recently - and the way we respond to this latest setback is critical if we're to buy more time. The NYT quoted Col. Alan J. Magill from the Walter Reed Army Institute of Research in Maryland: "Many of us think this should be treated on the same order as SARS," said Magill. "This should be a global emergency that is addressed in a global fashion."
We should look for broader lessons from this frightening scenario of malaria and artemisinin in South East Asia, and indeed from SARS and other emerging infectious diseases. We know that, even with good prevention efforts, diseases will still spread and drug resistant parasites will emerge. We know that containment is more effective than trying to keep pace with resistance trends by developing new drugs. Perhaps we should try and get ahead, at least for priority diseases with limited treatment options, by developing step-wise containment strategies well before resistance emerges and then deploying them rapidly in response to defined "triggers." In other words, close it down before it becomes everyone's problem.
This would mean dramatically enhancing drug resistance surveillance efforts, using early warning indicators based on treatment outcomes as well as drug susceptibility testing where appropriate. Not easy, and not cheap - but perhaps more affordable than the alternatives and surely worth it to save millions of lives. We've recently had the opportunity to sit down with people from CDC and learned more about the CDC's Global Disease Detection centers around the world, one of which is in Thailand. They are the world's experts on surveillance and disease detection. They have the nimbleness and knowledge to attack resistance problems "like SARS." But the Centers are few and far between (there are 6 globally) and their activities are driven by gyrating budgets. We think there would be great benefit in building on their existing emergency response systems to improve surveillance and react rapidly to drug resistance, not just for anti-malarials, but for all drugs used to treat the infectious diseases afflicting poor and vulnerable people.
Back in Thailand and Cambodia, a "containment" strategy is taking shape in an effort to halt the spread of artemisinin-resistant malaria. The aim is to prevent infections as well as improve cure rates, with an emphasis on increasing bednet use and proactively screening local people so those infected are treated more rapidly and more effectively. Those of us outside the region must watch and learn .. and hope it works.
If you are interested in the global problem of drug resistance and what can be done about it, please see the Center for Global Development's Drug Resistance Working Group and sign up for the monthly newsletter.